I've heard of it being done in a steel mill water reclamation system where the original cast iron piping was rotting out inside of cement floors etc due to the corrosive/leeching by incoming low pH waste water.

Going up through walls is easy, often just 2 small holes in the wall, one to drill the plate and and one for the cat, the cross piece between studs usually halfway up a wall. fishing in the direction of the joists is easy, going across them can be done with small holes spanning the joist, notching it for the cable, and then put a steel plate over it.Given that your problem unit is ground floor, it's likely you can fish up from the basement very easily for outlets using "old work" steel boxes, plastic boxes don't work with plaster on lath, it's too thick.

We have "RENT" slot on the front of our building if tenants want to drop off a check

Tariffs are a factor, mainly on certain materials like steel, but not a huge factor overall   Without knowing many of the specifics, or finish out levels of your project, I would expect to be able to build something like this for around half of what you are being quoted.My guess is the reason for high quotes is that because the demand for construction is so high, and contractors are backed up with as much business as they can handle, they are throwing out very high prices.I would keep shopping, and if you have experience, consider GC’ing it yourself, and hiring the expertise in the places you need it.

As for mobile homes, if they have no steel girders under them, called stick built, they do gain value if set on a foundation not in a park.

Cost of steel and labor are up for developers.Unless the land is dirt cheap then do not look for a quick sale.

We're home to Winchester ammunition, a couple of Steel Mills, a glass factory, the box company, all of which are gone.

The guys you see working on the large upright structures of steel at a petrochemical refinery. 

If you are going to invest in rentals, or flips, or even successful wholesaling, you better steel up and prepare to work, or you are going to be decimated by those around you that *do* work. 

Cardone pitching his lastest deal on a recent podcast.  Del Ray something $92,000,000.    10 days to closing and he isnt oversubscribed.  $100,000 and you are in.PS...10 days are up.Is that possible.